KR20210134775A - Protection element and battery pack - Google Patents

Abstract

Provided are a protection device capable of cutting off a current path safely and quickly because a spark is unlikely to occur even when a high voltage is applied, and a battery pack using the same. An insulating substrate 2, a fuse element 3, a heating element 4 for fusion cutting the fuse element 3 by heat generation, a heating element feeding electrode 5 serving as a power supply terminal to the heating element 4, and a heating element ( 4) an insulating layer 6 covering the insulating layer 6 and a heating element lead-out electrode 7 formed along the heating element 4 on the insulating layer 6 and holding the molten conductor 3a of the fuse element 3 When the heating element 4 is energized, the heating element feeding electrode 5 side becomes a high potential part, the heating element extraction electrode 7 side becomes a low potential part, and the heating element extraction electrode 7 becomes the heating element 4 The overlapping area of the distal end portion 7a extending toward the high potential portion and the heating element 4 is smaller than the overlapping area of the base portion 7b extending toward the low potential portion of the heating element 4 and the heating element 4 .

Description

Protection element and battery pack

The present technology relates to a protection element that protects a circuit connected on a current path by fusing the current path, and a battery pack using the same. This application claims priority on the basis of Japanese Patent Application No. Japanese Patent Application No. 2019-074956 for which it applied in Japan on April 10, 2019, This application is used for this application by reference.

Most of the rechargeable batteries that can be recharged and used repeatedly are processed into battery packs and provided to users. In particular, in a lithium ion secondary battery having a high weight energy density, in order to ensure the safety of users and electronic devices, in general, several protection circuits such as overcharge protection and overdischarge protection are built into the battery pack, It has a function to cut off the output of the battery pack.

In an electronic device using many lithium ion secondary batteries, the overcharge protection or overdischarge protection operation of a battery pack is performed by performing ON/OFF of an output using the FET switch built into a battery pack. However, even if the FET switch is short-circuited and destroyed for some reason, when a momentary large current flows due to a lightning surge, etc., or when the output voltage is abnormally lowered due to the life of the battery cell, or, conversely, even when an excessive abnormal voltage is output. A battery pack or an electronic device must be protected from accidents such as ignition. Therefore, in order to safely cut off the output of the battery cell in any conceivable abnormal state, a protection element composed of a fuse element having a function of blocking a current path by a signal from the outside is used.

As a protection element of a protection circuit suitable for such a lithium ion secondary battery etc., the structure which has a heating element inside a protection element, and cuts the soluble conductor on a current path by fusion is used by heat_generation|fever of this heating element.

The use of lithium ion secondary batteries has been expanding in recent years, and adoption is being considered for use of larger currents, for example, electric tools such as electric drivers, and transportation equipment such as hybrid cars, electric vehicles, and electric electric bicycles, and is partially adopted. This is disclosed. In such a use, a large current exceeding several 10 A to 100 A may flow, especially at the time of start-up. Realization of a protection element corresponding to such a large current capacity is desired.

In order to implement|achieve the protection element corresponding to such a large current, the protection element which used the soluble conductor which increased the cross-sectional area, and connected the insulating board which provided the heat generating body to the surface of this soluble conductor is proposed.

25 : is a figure which shows one structural example of the conventional protection element, (A) is a top view which abbreviate|omits a cover member and shows, (B) is sectional drawing, (C) is a bottom view. The protection element 100 shown in FIG. 25 includes an insulating substrate 101 , first and second electrodes 102 and 103 formed on the surface of the insulating substrate 101 , and on the surface of the insulating substrate 101 . The formed heating element 104, the insulating layer 105 covering the heating element 104, the heating element withdrawing electrode 106 laminated on the insulating layer 105 and connected to the heating element 104, and a first electrode ( 102 , a fuse element 107 mounted over the heating element lead-out electrode 106 , and the second electrode 103 via a solder for connection.

The first and second electrodes 102 and 103 are terminal portions connected on a current path of an external circuit to which the protection element 100 is connected, and first and second external connections formed on the back surface of the insulating substrate 101, respectively. It is connected to the electrodes 102a and 103a through a castellation. In the protection element 100 , the first and second external connection electrodes 102a and 103a are connected to connection electrodes provided on an external circuit board on which the protection element 100 is mounted, so that the fuse element 107 is connected to the external circuit board. embedded in part of the current path formed on it.

The heating element 104 is a member having a relatively high resistance value and is a conductive member that generates heat when energized, and is made of, for example, nichrome, W, Mo, Ru, or the like, or a material containing these. Further, the heating element 104 is connected to the heating element feeding electrode 108 formed on the surface of the insulating substrate 101 . The heating element feeding electrode 108 is connected to the third external connection electrode 108a formed on the back surface of the insulating substrate 101 via a castel. In the protection element 100, the third external connection electrode 108a is connected to a connection electrode provided on an external circuit board on which the protection element 100 is mounted, whereby the heating element 104 is connected to an external power supply provided in the external circuit. . In addition, as for the heat generating element 104, electric current and heat generation are always controlled by a switch element etc. which are not shown in figure.

The heating element 104 is covered with an insulating layer 105 made of a glass layer or the like, and the heating element extraction electrode 106 is formed on the insulating layer 105 , so that the heating element extraction electrode is interposed through the insulating layer 105 . (106) is superimposed. Further, on the heating element lead-out electrode 106, a fuse element 107 connected between the first and second electrodes 102 and 103 is connected.

Thereby, the protection element 100 is thermally connected by overlapping the heating element 104 and the fuse element 107, and when the heating element 104 generates heat by energization, the fuse element 107 can be cut by melting.

The fuse element 107 is formed of a low-melting-point metal such as Pb-free solder, or a high-melting-point metal such as Ag, Cu, or an alloy having these as a main component, or has a laminated structure of a low-melting-point metal and a high-melting-point metal. In addition, the fuse element 107 is connected from the first electrode 102 to the heating element extraction electrode 106 to the second electrode 103 , so that a part of the current path of the external circuit in which the protection element 100 is incorporated. make up Then, the fuse element 107 is fused by self-heating (Joule heat) when a current exceeding the rating is applied, or is fused by heat of the heating element 104, so that the first and second electrodes 102 and 103 are fused. block the liver

Then, when it is necessary to cut off the current path of the external circuit, the protection element 100 is energized by the switch element to the heating element 104 . As a result, in the protection element 100 , the heating element 104 is heated at a high temperature, and the fuse element 107 built in the current path of the external circuit is melted. The molten conductor of the fuse element 107 is drawn close to the heat generating element extraction electrode 106 and the first and second electrodes 102 and 103 with high wettability, whereby the fuse element 107 is fused. Accordingly, the protection element 100 may cut the gap between the first electrode 102 and the heating element lead-out electrode 106 to the second electrode 103 to block the current path of the external circuit.

Moreover, as a protection element, as shown in FIG. 26 besides the structure shown in FIG. 25, the thing provided with the two heat generating elements 104 is proposed. In the protection element 110 shown in FIG. 26 , two heat generating elements 104 are provided in parallel between the first and second electrodes 102 and 103 on the surface of the insulating substrate 101 . Each heating element 104 is covered with an insulating layer 105 , and a heating element lead-out electrode 106 provided on the insulating layer 105 is overlapped so as to span between both heating elements 104 .

Further, in the protection element 110 shown in FIG. 26 , the collecting electrode 111 is formed on the back surface of the insulating substrate 101 , and a plurality of penetrating elements between the heating element extraction electrode 106 and the collecting electrode 111 are formed. A through hole 112 is provided. The collecting electrode 111 and the through hole 112 attract the molten conductor of the fuse element 107 molten on the heating element lead-out electrode 106 and hold the molten conductor of the fuse element 107 which is enlarged in response to a large current application. The carrying capacity is increased, and a conductive layer is formed on the inner peripheral surface of the through hole 112 .

Japanese Patent Laid-Open No. 2018-78046

In a conventional structure such as the protection element 100 shown in FIG. 25 or the protection element 110 shown in FIG. 26, when used in a protection circuit of a lithium ion secondary battery for a large current application, power is supplied to the heating element 104 Since the lithium ion secondary battery for the high current is used as the external power source, a high voltage is applied to the heating element feeding electrode 108 when the protection element 100 is operated.

For this reason, in the protection element 100, as shown in FIG. 27, a spark (discharge) is generated from the heating element feeding electrode 108 to the tip of the heating element extraction electrode 106, and the heating element extraction electrode 106 is It may be damaged. And, when the heating element lead-out electrode 106 is damaged, the thermal conductivity to the fuse element 107 at the damaged location is lowered, and the time until the fuse element 107 is blown by melting is prolonged, so that the current path cannot be cut off quickly and safely. There are concerns.

In addition, as shown in Fig. 28, also in the protection element 110, when a spark is generated at the tip of the heating element lead-out electrode 106 from the heating-element feeding electrode 108 and the heating-element lead-out electrode 106 is damaged, the damaged location , the thermal conductivity to the fuse element 107 is lowered, and the time until the fuse element 107 is melted is prolonged, and there is a risk that the current path cannot be cut off quickly and safely. In addition, the insulating layer (glass layer) 105 is formed as thin as 10 to 40 µm in thickness in order to efficiently transfer the heat of the heating element 104 to the heating element extraction electrode 106 and the fuse element 107 . , the heat of the heating element 104 may be applied over a long period of time, resulting in damage. And, as shown in FIG. 29 , there is a fear that sparks may be generated in the central portion of the heating element lead-out electrode 106 from the high potential side of the heating element 104 at the damaged portion of the insulating layer 105 . As a result, when the heating element extraction electrode 106 is damaged, the thermal conductivity to the fuse element 107 is lowered due to the failure of the heating element extraction electrode 106 in addition to the destruction of the insulating layer 105 , and thus the fuse element 107 is to be blown by melting. There is a possibility that the time until the time is extended, making it impossible to cut off the current path quickly and safely.

The risk that the fuse element is melted and left behind due to electrode destruction accompanying such sparks and current interruption is inhibited, as the size of the fuse element increases with the increase in voltage and current, and as the current rating improves and the electric field strength increases, further, The size of the protective element increases with the increase in the proximity of the heating element feeding electrode 108 and the heating element extraction electrode 106 accompanying the miniaturization of the protection element and reduction of the thickness of the insulating layer.

Therefore, in the protection element with a built-in heating element, a countermeasure which respond|corresponds to a high voltage and a large current, and does not generate|occur|produce an electrode breakdown inside an element, and operates more safely and quickly is calculated|required.

Therefore, an object of the present technology is to provide a protection element that is less likely to generate a spark even when a high voltage is applied, and can safely and quickly cut off a current path, and a battery pack using the same.

In order to solve the above problems, the protection element according to the present technology includes an insulating substrate, a fuse element provided on one side of the insulating substrate, and a heating element formed on the insulating substrate to fuse the fuse element by heat generation; , a heating element feeding electrode connected to one end of the heating element as a power supply terminal to the heating element, an insulating layer covering the heating element, and the other end of the heating element being connected to the other end of the heating element and formed along the heating element on the insulating layer, has a heating element lead-out electrode in which the molten conductor of the fuse element is held, and the heating element, when energized through the heating element-feeding electrode, the heating element-feeding electrode side becomes a high-potential part, and the heating-element lead-out electrode side becomes a low-potential part , In the heating element lead-out electrode, the overlapping area of the front end portion extending toward the high potential portion of the heating element and the heating element is smaller than the overlapping area of the base portion extending toward the low potential portion of the heating element and the heating element.

In addition, the battery pack according to the present technology includes one or more battery cells, a protection element connected on a charge/discharge path of the battery cell to block the charge/discharge path, and a voltage value of the battery cell by detecting the A current control element for controlling conduction to the protection element is provided, wherein the protection element includes an insulating substrate, a fuse element provided on one side of the insulating substrate, and a fuse element formed on the insulating substrate to heat the fuse element by heat. A heating element to be cut by melting, a heating element feeding electrode connected to one end of the heating element as a power supply terminal to the heating element, an insulating layer covering the heating element, and the other end of the heating element connected to the insulating layer, the heating element is formed on the insulating layer and a heating element lead-out electrode in which the molten conductor of the fuse element is held. The heating element lead-out electrode is a low-potential portion, and the overlapping area of the front end portion extending toward the high-potential portion of the heating element and the heating element is smaller than the overlapping area of the base portion and the heating element extending toward the low-potential portion of the heating element.

According to the present technology, although the tip of the heating element lead-out electrode extends toward the high potential portion of the heating element, the overlapping area with the heating element is smaller than the overlapping area between the base and the heating element. As a result, the distance and the opposing area (overlapping area) of the front end of the heating element to the high-potential portion of the heating element are reduced, making it difficult to form a discharge path and thus making it difficult to generate sparks. Therefore, it is difficult to generate a spark even when a high voltage is applied, so that the current path can be cut off safely and quickly.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows 1st Embodiment of the protection element to which this technology was applied, (A) is a top view, (B) is sectional drawing, (C) is a bottom view.
2 is a view showing a state in which a fuse element is fused in a protection element to which the present technology is applied, (A) is a plan view, (B) is a cross-sectional view.
3 is a view showing a modified example of the heating element extraction electrode in the protection element to which the present technology is applied, (A) is a plan view, (B) is a cross-sectional view.
4 is a view showing a modified example of a heating element extraction electrode in a protection element to which the present technology is applied, (A) is a plan view, (B) is a cross-sectional view.
5 is an external perspective view of a fuse element.
6 is a circuit diagram showing a configuration example of a battery pack.
7 is a circuit diagram of the protection element according to the first embodiment.
It is a figure which shows the protection element which concerns on a comparative example, (A) is a top view, (B) is sectional drawing, (C) is a bottom view.
9 is a plan view illustrating a state in which a fuse element is not fused by melting and remaining in a protection element according to a comparative example.
It is a figure which shows 2nd Embodiment of the protection element to which this technology was applied, (A) is a top view, (B) is sectional drawing, (C) is a bottom view.
Fig. 11 is a plan view showing a modified example of the heating element lead-out electrode in the protection element according to the second embodiment.
12 is a circuit diagram of a protection element according to the second embodiment.
Fig. 13 is a plan view showing a modified example of the heat generating element lead-out electrode in the protection element according to the second embodiment.
Fig. 14 is a plan view showing a modified example of the heat generating body lead-out electrode in the protection element according to the second embodiment.
15 is a view showing a modified example in which a holding electrode for holding a molten conductor of a fuse element is formed on the back surface of an insulating substrate in the protection element according to the second embodiment, (A) is a plan view, (B) ) is a cross-sectional view, (C) is a bottom view.
Fig. 16 is a view showing a state in which the fuse element is fused in the protection element shown in Fig. 15, (A) is a plan view, (B) is a sectional view.
17A to 17D are plan views showing a modified example of the heating element in the protection element according to the second embodiment.
18 : is a figure which shows 3rd Embodiment of the protection element to which this technology was applied, (A) is a top view, (B) is sectional drawing, (C) is a bottom view.
19 is a cross-sectional view showing a state in which the fuse element is blown by fusion in the protection element according to the third embodiment.
20 is a cross-sectional view illustrating a configuration in which a fuse element is clamped by a plurality of fusing members.
Fig. 21 is a circuit diagram of the protection element shown in Fig. 20;
Fig. 22 is a cross-sectional view showing a state in which the fuse element is fused in the protection element shown in Fig. 20;
23 : is a figure which shows the protection element which concerns on the comparative example, (A) is a top view, (B) is sectional drawing, (C) is a bottom view.
24 is a plan view illustrating a state in which a fuse element is not fused by melting and remaining in the protection element according to the comparative example.
25 : is a figure which shows the conventional protection element, (A) is a top view, (B) is sectional drawing, (C) is a bottom view.
26 : is a figure which shows the conventional protection element, (A) is a top view, (B) is sectional drawing, (C) is a bottom view.
Fig. 27 is a plan view showing a state in which sparks are generated in the protection element shown in Fig. 25;
Fig. 28 is a plan view showing a state in which sparks are generated in the protection element shown in Fig. 26;
Fig. 29 is a plan view showing a state in which sparks are generated in the protection element shown in Fig. 26;

Hereinafter, a protection element and a battery pack to which the present technology is applied will be described in detail with reference to the drawings. In addition, this technique is not limited only to the following embodiment, It goes without saying that various changes are possible within the range which does not deviate from the summary of this technique. In addition, the drawings are schematic, and the ratio of each dimension, etc. may differ from an actual thing. Specific dimensions and the like should be determined in consideration of the following description. It goes without saying that parts having different dimensional relationships and ratios are included in the drawings as well.

[First Embodiment: Heating Element Overlap Structure]

A first embodiment of the protection element to which the present technology is applied will be described. The protection element 1 to which this technology was applied, as shown in FIGS. 3), a heating element 4 formed on the insulating substrate 2 and fusing the fuse element 3 by heat generation, and a heating element feeding terminal connected to one end of the heating element 4 to serve as a power supply terminal to the heating element 4 The electrode 5, the insulating layer 6 covering the heating element 4, and the other end of the heating element 4 are connected, are formed on the insulating layer 6 along the heating element 4, and the fuse element 3 ) has a heating element lead-out electrode 7 on which the molten conductor 3a is held.

Moreover, in the heating element 4, when electricity is supplied through the heating element feeding electrode 5, the heating element feeding electrode 5 side becomes a high potential part, and the heating element lead-out electrode 7 side becomes a low potential part. And, the heating element lead-out electrode 7 has a tip portion 7a extending toward the high potential portion of the heating element 4 and a base portion 7b in which the overlapping area of the heating element 4 extends toward the low potential portion side of the heating element 4 and It is characterized in that it is smaller than the overlapping area of the heating element (4).

Accordingly, the protection element 1 can cut off the current path safely and quickly because sparks (discharge) do not easily occur even when a high voltage is applied. This is considered to be based on the following reasons.

That is, the spark is a phenomenon in which a large current flows instantaneously when dielectric breakdown occurs between the electrodes facing each other through the insulating layer from the high potential portion to the low potential portion. As for the heating element 4 connected to an external power supply and to which a high voltage is applied, one end connected to the heating element feeding electrode 5 has a higher potential than the other end connected to the heating element extraction electrode 7 . The tip portion 7a of the heating element lead-out electrode 7 extends toward the high potential portion of the heating element 4 , and the overlapping area with the heating element 4 is smaller than the overlapping area of the base portion 7b with the heating element 4 . As a result, the distance and the opposing area (overlapping area) of the distal end portion 7a of the heat generating element 4 with the high-potential portion becomes small, making it difficult to form a discharge path and thus making it difficult to generate sparks.

In addition, although the base portion 7b of the heating element lead-out electrode 7 has a relatively large overlapping area with the heating element 4, it is provided at a position spaced apart from the high potential portion of the heating element 4 and is formed with the base portion 7b and Since the other end side of the overlapping heating elements 4 is a low-potential part due to a voltage drop, it is a part where sparks are less likely to occur. For this reason, it becomes difficult to generate|occur|produce a spark also in the base part 7b.

The protection element 1 is built into an external circuit, so that the fuse element 3 forms a part of the current path of the external circuit, and the current is cut by heat generation of the heating element 4 or overcurrent exceeding the rating. block the path Hereinafter, each structure of the protection element 1 is demonstrated in detail.

[Insulation Substrate]

The insulating substrate 2 is formed of, for example, an insulating member such as alumina, glass ceramics, mullite, or zirconia. In addition, the insulating board 2 may use the material used for printed wiring boards, such as a glass epoxy board|substrate and a phenol board|substrate.

First and second electrodes 11 and 12 are formed at opposite ends of the insulating substrate 2 . The first and second electrodes 11 and 12 are each formed of a conductive pattern such as Ag or Cu. Further, on the surfaces of the first and second electrodes 11 and 12, a film such as Ni/Au plating, Ni/Pd plating, and Ni/Pd/Au plating is coated by a known method such as plating treatment. desirable. Thereby, the protection element 1 can prevent oxidation of the 1st, 2nd electrodes 11 and 12, and can prevent the fluctuation|variation of the rating accompanying a raise of conduction resistance. In addition, when the protection element 1 is reflow mounted, the solder for connection connecting the fuse element 3 is melted, thereby preventing the first and second electrodes 11 and 12 from being eroded (solder erosion). can do.

Further, the first and second electrodes 11 and 12 are first and second external connection electrodes 11a and 12a formed from the front surface 2a of the insulating substrate 2 to the back surface 2b through casting. ) and is continuous. The protection element 1 includes first and second external connection electrodes 11a and 12a formed on the back surface 2b of the insulating substrate 2 to the connection electrodes provided on the external circuit board on which the protection element 1 is mounted. By being connected, the fuse element 3 is embedded in a part of the current path formed on the circuit board.

The first and second electrodes 11 and 12 are electrically connected by mounting the fuse element 3 with a conductive connection material such as a connection solder 9 . In addition, as shown in FIG. 2 , in the first and second electrodes 11 and 12 , a large current exceeding the rating flows to the protection element 1 , and the fuse element 3 is fused by self-heating (Joule heat). Alternatively, the heat generating element 4 generates heat according to the energization, and the fuse element 3 is cut by melting.

[Heating element]

The heat generating element 4 has a relatively high resistance value and is a conductive member that generates heat when energized, and is made of, for example, nichrome, W, Mo, Ru or the like or a material containing these. The heat generating element 4 is formed by mixing these alloys, compositions, or powders of the compound with a resin binder, etc., and forming a paste on the insulating substrate 2 using a screen printing technique to form a pattern, followed by firing. can

Further, the heating element 4 has one end connected to the heating element feeding electrode 5 and the other end connected to the heating element electrode 8 . The heating element feeding electrode 5 and the heating element electrode 8 are formed in mutually opposing side edges different from the side edges in which the first and second electrodes 11 and 12 of the insulating substrate 2 are provided. The heating element feeding electrode 5 is an electrode that is connected to one end of the heating element 4 to serve as a power supply terminal to the heating element 4 , and is a third external connection formed on the back surface 2b of the insulating substrate 2 through casting. It is continuous with the electrode 5a. The heating element electrode 8 is connected to the heating element extraction electrode 7 .

In addition, the heating element 4 is covered with the insulating layer 6 and overlaps with the heating element extraction electrode 7 formed on the insulating layer 6 . The fuse element 3 provided across the 1st, 2nd electrodes 11 and 12 is connected to the heat generating body lead-out electrode 7 via bonding materials, such as a connection solder 9,.

The insulating layer 6 is provided in order to protect and insulate the heating element 4 and efficiently transfer the heat of the heating element 4 to the heating element extraction electrode 7 and the fuse element 3, for example, It consists of a glass layer. In order to transmit the heat|fever of the heat generating body 4 efficiently to the heat generating body lead-out electrode 7 and the fuse element 3, the insulating layer 6 is formed thin, for example to 10-40 micrometers in thickness.

The heating element 4 is connected to a current control element or the like formed in an external circuit through the third external connection electrode 5a by mounting the protection element 1 on an external circuit board, so that current and heat generation are normally regulated. have. Then, the heating element 4 is energized through the third external connection electrode 5a at a predetermined timing when the energization path of the external circuit is cut off, and generates heat. At this time, as for the heating element 4, the heating element feeding electrode 5 side becomes a high potential part, and the heating element extraction electrode 7 side becomes a low potential part. The protection element 1 connects the 1st, 2nd electrodes 11 and 12 by the heat|fever of the heating element 4 being transmitted to the fuse element 3 through the insulating layer 6 and the heating-element lead-out electrode 7. The current fuse element 3 can be melted. The molten conductor 3a of the fuse element 3 is aggregated on the heating element lead-out electrode 7 and on the first and second electrodes 11 and 12, and thereby between the first and second electrodes 11 and 12. The current path is blocked. Further, in the heat generating element 4 , when the fuse element 3 is fused, heat generation is stopped because its own electricity supply path is also cut off.

In addition, in the heating element feeding electrode 5, the connection solder provided on the electrode of the external circuit board connected to the third external connection electrode 5a is melted in reflow mounting or the like, and the heating element feeding electrode 5 is cast through the casting. ), it is preferable to provide a regulating wall 17 that prevents it from spreading onto the heating element feeding electrode 5 . The regulating wall 17 can be formed using, for example, an insulating material that does not have wettability to solder, such as glass, solder resist, and an insulating adhesive, and can be formed on the heating element feeding electrode 5 by printing or the like. By providing the regulating wall 17, it is possible to prevent the molten solder for connection from spreading to the heating element feeding electrode 5, thereby maintaining the connectivity between the protection element 1 and the external circuit board.

[Heating element extraction electrode]

Like the first and second electrodes 11 and 12 , the heating element extraction electrode 7 is formed of a conductive pattern such as Ag or Cu. In addition, it is preferable that a film such as Ni/Au plating, Ni/Pd plating, and Ni/Pd/Au plating is coated on the surface of the heating element lead-out electrode 7 by a known method such as plating treatment.

The heat generating body lead-out electrode 7 is formed on the insulating layer 6 while one end is connected to the heat generating body electrode 8 and overlaps the heat generating body 4 via the insulating layer 6 . As described above, the heating element lead-out electrode 7 has a tip portion 7a extending toward the high potential portion side of the heating element 4 when energized, and a base portion 7b extending toward the low potential portion side, and the tip portion 7a The overlapping area S1 of the heating element 4 and the base portion 7b is smaller than the overlapping area S2 of the base portion 7b and the heating element 4 . Accordingly, the protection element 1 can block the current path safely and quickly because sparks (discharge) do not easily occur even when a high voltage is applied from an external circuit.

Here, when the direction orthogonal to the energization direction of the heating element 4 is the width direction of the heating element lead-out electrode 7, the protection element 1 has a wide site|part provided on the low-potential part side, and the high-potential part side. It has a narrow part which is provided and protrudes from the wide part, let the said wide part be the base part 7b, and let the narrow part which protrudes from the base part 7b be the front-end|tip part 7a. In addition, in the heating element lead-out electrode 7 , the overlapping area S1 between the tip portion 7a and the heating element 4 is smaller than the overlapping area S2 between the base portion 7b and the heating element 4 .

Accordingly, as shown in Fig. 1, even when the entire tip portion 7a overlaps with the heating element 4, the protection element 1 generates a spark (discharge) when a high voltage is applied from an external circuit. It is unlikely to occur, so it can break the current path safely and quickly.

In addition, by providing the wide base portion 7b on the heating element lead-out electrode 7 , the capacity for holding the molten conductor 3a of the fuse element 3 can be increased, and the fuse element 3 can be reliably can be forged. That is, the heating element extraction electrode 7 can be prevented from sparking by providing the narrow tip portion 7a. On the other hand, if the area of the heating element extraction electrode 7 is reduced, when the fuse element 3 is melted. , the capacity for holding the molten conductor 3a decreases, and the molten conductor 3a overflowing from the heating element lead-out electrode 7 comes into contact with the molten conductor 3a on the first and second electrodes 11 and 12 to conduct electricity. There is also a risk that the route cannot be blocked. In this respect, the heat generating body lead-out electrode 7 can increase the capacity for holding the molten conductor 3a by forming the wide base portion 7b, so that the fuse element 3 can be cut by fusing reliably. (Fig. 2).

In addition, as shown in FIG. 1, the protection element 1 is in the said assumed area|region in the case where it is assumed that the front-end|tip part 7a of the heat generating body lead-out electrode 7 has the same width as the base part 7b. In this case, it is preferable that the overlapping area S1 with the heating element 4 is smaller than the non-overlapping area S3 with the heating element in the assumed region. In the protection element 1 shown in FIG. 1, the non-overlapping area S3 in the assumed area|region means the total area of the both sides of the front-end|tip part 7a.

As for the tip portion 7a, in the assumed region, the overlapping area S1 of the heating element 4 with the high-potential portion is smaller than the non-overlapping area S3 with the high-potential portion, so that the discharge path becomes difficult to form and sparks difficult to occur.

Moreover, as for the heat generating body lead-out electrode 7, as shown in FIG. 1, it is preferable that the area of the front-end|tip part 7a is smaller than the area of the base part 7b. Accordingly, even when the entire tip portion 7a is overlapped with the heating element 4, the protection element 1 is less likely to generate a spark (discharge) when a high voltage is applied from an external circuit, so that a current safely and quickly. path can be blocked.

3 and 4 are modified examples of the heating element lead-out electrode 7 . The heat generating body lead-out electrode 7 may form the front-end|tip part 7a in a substantially trapezoidal shape or a triangular shape. In addition, the fuse element 3 is abbreviate|omitted in FIG.3, FIG.4.

Further, as shown in FIG. 1 , the fuse element 3 is mounted on the heating element extraction electrode 7 , and the tip portion 7a of the heating element extraction electrode 7 is a heating element rather than the side edge of the fuse element 3 . It is preferable not to protrude toward the feeding electrode 5 side. Since a high voltage is applied to the heating element feeding electrode 5 and a high potential is obtained, the heating element lead-out electrode 7 is retracted from the fuse element 3 to the low-potential portion side, so that the heating element extraction electrode 7 can be separated from the high-potential portion. Further, if the tip portion 7a of the heating element lead-out electrode 7 protrudes toward the heating element feeding electrode 5 side rather than the side edge portion of the fuse element 3, the tip portion 7a may act as a lightning rod. Since no negative site is formed, the risk of spark generation can be reduced. In addition, the volume of the metal (i.e., the tip portion 7a and the fuse element 3) opposing the heating element feeding electrode 5, which becomes high potential by overlapping the heating element lead-out electrode 7 and the fuse element 3, increases, Even in the event of a spark, the resistance to impact is improved and damage is prevented.

[Fuse Element]

Next, the fuse element 3 is demonstrated. The fuse element 3 is mounted across the first and second electrodes 11 and 12, and is fused by self-heating (Joule heat) when the heat generation element 4 is energized or a current exceeding the rating is passed through. Thus, the current path between the first electrode 11 and the second electrode 12 is blocked.

The fuse element 3 may be a conductive material that is heated by energization of the heating element 4 or a conductive material melted by an overcurrent state, for example, in addition to SnAgCu-based Pb-free solder, BiPbSn alloy, BiPb alloy, BiSn alloy, SnPb alloy, PbIn alloy, ZnAl alloy, InSn alloy, PbAgSn alloy, etc. can be used.

In addition, the fuse element 3 may be a structure containing a high-melting-point metal and a low-melting-point metal. For example, as shown in FIG. 5 , the fuse element 3 is a laminate structure comprising an inner layer and an outer layer, and a low melting point metal layer 13 as an inner layer and a high melting point as an outer layer laminated on the low melting point metal layer 13 . It has a metal layer (14). The fuse element 3 is connected on the first and second electrodes 11 and 12 and the heating element lead-out electrode 7 through a bonding material such as a connection solder 9 .

The low-melting-point metal layer 13 is preferably solder or a metal containing Sn as a main component, and is a material generally called “Pb-free solder”. The melting point of the low-melting-point metal layer 13 is not necessarily higher than the reflow furnace temperature, and may be melted at about 200°C. The high-melting-point metal layer 14 is a metal layer laminated on the surface of the low-melting-point metal layer 13, for example, Ag or Cu, or a metal mainly composed of any of these, and the first and second electrodes 11 and 12. And it has a high melting|fusing point which does not melt even when the connection of the heat generating body extraction electrode 7 and the fuse element 3 or mounting on the external circuit board of the protection element 1 is performed by reflow.

Such a fuse element 3 can be formed by forming a high-melting-point metal layer into a film on low-melting-point metal foil using a plating technique, or can also be formed using other well-known lamination technique and film formation technique. In this case, the fuse element 3 may have a structure in which the entire surface of the low-melting-point metal layer 13 is covered with the high-melting-point metal layer 14 , or may have a structure in which the entire surface of the low-melting-point metal layer 13 is covered except for a pair of side surfaces facing each other. In addition, the fuse element 3 may use the high-melting-point metal layer 14 as an inner layer and the low-melting-point metal layer 13 as an outer layer, and may be comprised, and also three or more layers in which a low-melting-point metal layer and a high-melting-point metal layer are laminated|stacked alternately. It can be formed by various structures, such as setting it as a multilayer structure, or providing an opening part in part of an outer layer to expose part of an inner layer.

The fuse element 3 laminates the high-melting-point metal layer 14 as an outer layer on the low-melting-point metal layer 13 serving as the inner layer, so that even when the reflow temperature exceeds the melting temperature of the low-melting-point metal layer 13 , the fuse As the element 3, the shape can be maintained, and it does not lead to melting. Therefore, the connection of the first and second electrodes 11 and 12 and the heating element lead-out electrode 7 and the fuse element 3 and the mounting of the protection element 1 on an external circuit board can be efficiently performed by reflow. In addition, even by reflow, the resistance value locally increases or decreases with the deformation of the fuse element 3, so that it does not melt at a predetermined temperature or is melted below a predetermined temperature, etc. It is possible to prevent fluctuations in the fusing characteristics.

Further, the fuse element 3 is not fused by self-heating while a predetermined rated current is flowing. Then, when a current having a value higher than the rating flows, it is melted by self-heating, and the current path between the first and second electrodes 11 and 12 is cut off. Further, the heating element 4 is energized and melted by generating heat, thereby blocking the current path between the first and second electrodes 11 and 12 .

At this time, in the fuse element 3 , the molten low-melting-point metal layer 13 erodes the high-melting-point metal layer 14 (solder erosion), so that the high-melting-point metal layer 14 is melted at a temperature lower than the melting temperature. Therefore, the fuse element 3 can be fused in a short time using the erosion action of the high-melting-point metal layer 14 by the low-melting-point metal layer 13 . In addition, since the molten conductor 3a of the fuse element 3 is divided by the physical drawing-in action of the heating element lead-out electrode 7 and the first and second electrodes 11, 12, A current path between the first and second electrodes 11 and 12 may be blocked ( FIG. 2 ).

In addition, in the fuse element 3 , it is preferable that the volume of the low-melting-point metal layer 13 is larger than the volume of the high-melting-point metal layer 14 . The fuse element 3 is heated by self-heating due to overcurrent or heat generated by the heating element 4 , and the low-melting-point metal is melted to erode the high-melting-point metal, thereby enabling rapid melting and fusion cutting. Accordingly, the fuse element 3 promotes this erosion action by forming the volume of the low-melting-point metal layer 13 to be larger than that of the high-melting-point metal layer 14, so that the first and second external connection electrodes 11, 12) It can block the liver.

In addition, since the fuse element 3 is constituted by laminating the high-melting-point metal layer 14 on the low-melting-point metal layer 13 as an inner layer, the fusing temperature can be significantly reduced compared to that of a conventional chip fuse made of a high-melting-point metal. can Accordingly, the cross-sectional area of the fuse element 3 can be increased compared to a chip fuse of the same size, and the current rating can be significantly improved. In addition, it is possible to achieve miniaturization and thickness reduction compared to the conventional chip fuses having the same current rating, so that it is excellent in fast melting properties.

In addition, the fuse element 3 can improve resistance (pulse resistance) to a surge in which an abnormally high voltage is instantaneously applied to the electric system in which the protection element 1 is built-in. That is, the fuse element 3 should not be fused by melting even when, for example, a current of 100 A flows for several msec. In this regard, since a large current flowing in a very short time flows through the surface layer of the conductor (skin effect), the fuse element 3 is provided with a high-melting-point metal layer 14 such as Ag plating having a low resistance value as an outer layer. It is easy to flow the electric current applied by this, and melting by self-heating can be prevented. Accordingly, the fuse element 3 can significantly improve the resistance to surges compared to a conventional fuse made of a solder alloy.

Further, the fuse element 3 may be coated with a flux (not shown) in order to prevent oxidation and improve wettability at the time of fusion cutting. In addition, the inside of the protection element 1 is protected by the insulating substrate 3 being covered by the case member (not shown). The case member can be formed using, for example, a member having insulating properties such as various engineering plastics, thermoplastic plastics, ceramics, and glass epoxy substrates. Further, in the case, on the surface 2a of the insulating substrate 2, the fuse element 3 expands to a spherical shape at the time of melting, and the molten conductor 3a is formed with the heating element lead-out electrode 7 or the first, second It has enough interior space to aggregate on the electrodes 11 and 12 .

[Circuit configuration example]

As shown in FIG. 6, such a protection element 1 is incorporated in the circuit in the battery pack 20 of a lithium ion secondary battery, and is used, for example. The battery pack 20 has the battery stack 25 which consists of battery cells 21a-21d of a total of four lithium ion secondary batteries, for example.

The battery pack 20 includes a battery stack 25 , a charge/discharge control circuit 26 for controlling charging and discharging of the battery stack 25 , and a main body for blocking a charging/discharging path when the battery stack 25 is abnormal. A protection element 1 to which the invention is applied, a detection circuit 27 for detecting the voltage of each battery cell 21a to 21d, and a detection result of the detection circuit 27 to control the operation of the protection element 1 A current control element 28 serving as a switch element is provided.

In the battery stack 25 , battery cells 21a to 21d that require control for protection from overcharge and overdischarge conditions are connected in series, and the positive electrode terminal 20a and the negative electrode terminal 20b of the battery pack 20 are connected in series. It is detachably connected to the charging device 22 via the , and a charging voltage from the charging device 22 is applied. The battery pack 20 charged by the charging device 22 can operate the electronic device by connecting the positive electrode terminal 20a and the negative electrode terminal 20b to an electronic device operated by a battery.

The charge/discharge control circuit 26 includes two current control elements 23a and 23b connected in series to a current path between the battery stack 25 and the charging device 22, and these current control elements 23a and 23b. and a control unit 24 for controlling the operation of The current control elements 23a and 23b are constituted by, for example, field effect transistors (hereinafter referred to as FETs), and by controlling the gate voltage by the control unit 24 , the current path of the battery stack 25 is charged. Controls the conduction blocking in the direction and/or discharge direction. The control unit 24 operates by receiving power supply from the charging device 22 , and according to the detection result by the detection circuit 27 , the current path is cut off when the battery stack 25 is overdischarged or overcharged. The operation of the control elements 23a and 23b is controlled.

The protection element 1 is connected on the charge/discharge current path between the battery stack 25 and the charge/discharge control circuit 26, for example, and its operation is controlled by the current control element 28. As shown in FIG.

The detection circuit 27 is connected to each battery cell 21a to 21d, detects the voltage value of each battery cell 21a to 21d, and sets each voltage value to the control unit 24 of the charge/discharge control circuit 26 supply to Further, the detection circuit 27 outputs a control signal for controlling the current control element 28 when any one of the battery cells 21a to 21d becomes an overcharge voltage or an overdischarge voltage.

The current control element 28 is constituted by, for example, an FET, and by a detection signal output from the detection circuit 27, the voltage value of the battery cells 21a to 21d exceeds a predetermined overdischarge or overcharge state. When the voltage reaches the desired voltage, the protection element 1 is operated to control the charging/discharging current path of the battery stack 25 to be cut off regardless of the switching operation of the current control elements 23a and 23b.

The protection element 1 to which this invention used for the battery pack 20 which consists of the above structures was applied has a circuit structure as shown in FIG. That is, in the protection element 1 , the first external connection electrode 11a is connected to the battery stack 25 side, and the second external connection electrode 12a is connected to the positive electrode terminal 20a side, whereby the fuse The element 3 is connected in series on the charge/discharge path of the battery stack 25 . Further, in the protection element 1, the heating element 4 is connected to the current control element 28 through the heating element feeding electrode 5 and the third external connection electrode 5a, and the heating element 4 is connected to the battery stack ( 25) is connected with the open end. As a result, the heating element 4 has one end connected to one open end of the fuse element 3 and the battery stack 25 via the heating element extraction electrode 7 , and the other end is connected to the third external connection electrode 5a via the third external connection electrode 5a. It is connected with the other open end of the current control element 28 and the battery stack 25 to form a power supply path to the heat generating element 4 whose energization is controlled by the current control element 28 .

[Operation of protection element]

When the detection circuit 27 detects an abnormal voltage of any of the battery cells 21a to 21d, it outputs a cutoff signal to the current control element 28 . Then, the current control element 28 controls the current so that the heating element 4 is energized. In the protection element 1, a current flows from the battery stack 25 to the heating element 4, whereby the heating element 4 starts to generate heat. In the protection element 1 , the fuse element 3 is fused by the heat of the heating element 4 , and the charging/discharging path of the battery stack 25 is blocked. In addition, the protection element 1 is formed by making the fuse element 3 contain a high-melting-point metal and a low-melting-point metal, so that the low-melting-point metal is melted before melting of the high-melting-point metal, and the high melting point by the molten low-melting-point metal The fuse element 3 can be melted in a short time by using the erosion action of the metal.

At this time, in the protection element 1, the tip portion 7a extending toward the high potential portion side of the heating element 4 when energized, and the overlapping area S1 of the heating element 4 have a base portion 7b extending toward the low potential portion side. ) and the overlapping area S2 of the heating element 4 are smaller. Thereby, the protection element 1 is less likely to generate a spark (discharge) even when a high voltage is applied to the heating element feeding electrode 5 from the battery stack 25 corresponding to a large current application, so that the current path is safely and quickly. can be blocked

In addition, since the protection element 1 has a narrow tip portion 7a protruding from the base portion 7b of the heating element lead-out electrode 7, the heat of the heating element 4 is concentrated on the tip portion 7a, High heat can be rapidly transferred from the tip portion 7a to the fuse element 3 . That is, since the protection element 1 has a narrow tip portion 7a, the heat of the heating element 4 is concentrated on the tip portion 7a without diffusing compared to a rectangular heating element extraction electrode, and is efficiently a fuse element. (3) can be forwarded. Therefore, even when the cross-sectional area of the fuse element 3 is increased in order to cope with a high current application, the protection element 1 can concentrate the heat on the tip portion 7a to rapidly cut the fuse element 3 by melting.

In the protection element 1 , when the fuse element 3 is fused, the power supply path to the heat generating body 4 is also cut off, so that the heat generation of the heat generating body 4 is stopped.

In addition, the protection element 1, even when an overcurrent exceeding the rating is applied to the battery pack 20, the fuse element 3 is melted by self-heating to block the charging/discharging path of the battery pack 20. can

As described above, in the protection element 1 , the fuse element 3 is fused by heat generated by the energization of the heat generating element 4 or by self-heating of the fuse element 3 due to overcurrent. At this time, when the protection element 1 is reflow mounted on a circuit board, or when the circuit board on which the protection element 1 was mounted is also exposed to high temperature environment, such as reflow heating, a low-melting-point metal is a high-melting-point metal. Since it has a structure covered with , deformation of the fuse element 3 is suppressed. Accordingly, variations in fusing characteristics due to variations in resistance values due to deformation of the fuse element 3 are prevented, and fusing can be performed quickly by a predetermined overcurrent or heat generation of the heating element 4 .

The protection element 1 according to the present invention is, of course, applicable not only to the case of use in a battery pack of a lithium ion secondary battery, but also to various uses requiring blocking of a current path by an electric signal.

first embodiment

Next, an embodiment of the protection element 1 will be described. In the first embodiment, the protection element 1 shown in Fig. 1 and the protection element provided with the rectangular heating element extraction electrode shown in Figs. 25 and 8 are prepared, and voltages of 50 V, 100 V, and 200 V are applied, respectively. The presence or absence of sparks at the time of doing this was determined. In addition, the fusing time of the fuse element was evaluated, and the case where the fuse element was fused within a predetermined time (60 seconds) was evaluated as ○ (good), and the case where the fuse was not fused within the predetermined time was evaluated as × (bad).

The dimension of each part of the protection element which concerns on an Example and a comparative example is defined as follows. In addition, the numerical value of each part shown in Table 1 is a numerical value which shows the ratio when E is set to 1.

D: distance between the tip of the heating element lead-out electrode and the heating element feeding electrode

E: Length in the energization direction of the heating element

F: Minimum width of the heating element lead-out electrode

G: Maximum width of the heating element lead-out electrode

L: Width between the side edge of the tip of the heating element lead-out electrode and the side edge of the base

P: overlapping length of the heating element lead-out electrode and the heating element

Q: Length of the base of the heating element lead-out electrode

[Example 1]

As the protection element according to Example 1, the one shown in FIG. 1 was used. In the protection element according to Example 1, a base portion (width G: 0.33) and a tip portion (width F: 0.1) are provided on the heating element lead-out electrode, and the base portion is formed to be 0.06 wider on one side than the tip portion. In addition, the heating element drawing electrode does not protrude toward the heating element feeding electrode side than the fuse element, so the distance (D) between the tip of the heating element extraction electrode and the heating element feeding electrode is 0.38, and the overlapping length (P) of the heating element extraction electrode and the heating element feeding electrode is set to 0.62.

[Comparative Example 1]

As the protection element according to Comparative Example 1, the one shown in FIG. 25 was used. In the protection element according to Comparative Example 1, a rectangular heating element extraction electrode (width: 0.21) was formed. In addition, the heating element drawing electrode protrudes toward the heating element feeding electrode side than the fuse element, the distance (D) between the tip of the heating element extraction electrode and the heating element feeding electrode is as short as 0.07, and the overlapping length (P) of the heating element extraction electrode and the heating element is 0.93 is made of

[Comparative Example 2]

As the protection element according to Comparative Example 2, the one shown in FIG. 8 was used. Similarly to Comparative Example 1, the protection element according to Comparative Example 2 uses a rectangular heating element lead-out electrode (width: 0.21). The difference from Comparative Example 1 is that, in the protection element according to Comparative Example 2, the heating-element lead-out electrode does not protrude toward the heating-element feeding electrode side than the fuse element. Thereby, in Comparative Example 2, the distance D between the front end of the heating element lead-out electrode and the heating element feeding electrode was secured by 0.38, and the overlapping length P between the heating element extraction electrode and the heating element was 0.62.

As shown in Table 2, in Example 1, no spark was generated even when any voltage was applied, and the fuse element could be blown by fusing within a predetermined time. On the other hand, in Comparative Example 1, sparks were generated even when any voltage was applied, and the fuse element could not be blown by fusing within a predetermined time. Further, in Comparative Example 2, no spark was generated even when any voltage was applied, but since a rectangular heating element extraction electrode having a narrow width of 0.21 was used, the capacity for holding the molten conductor of the fuse element was increased. In short, as shown in FIG. 9, a molten conductor was continuous between a 1st, 2nd electrode, and the fuse element could not be blown-off within a predetermined time.

[Second Embodiment: Surface Heating Element Both Side Structures]

Next, 2nd Embodiment of the protection element to which this technique was applied is demonstrated. In addition, in the following description, about the structure similar to the protection element 1 mentioned above, the same code|symbol is attached|subjected and the detail may be abbreviate|omitted. The protection element 30 which concerns on 2nd Embodiment, as shown to FIG. 10(A) - (C), the insulated substrate 2 and the fuse provided in the surface 2a side of the insulated substrate 2 The element 3, a plurality of heating elements 4 formed on the insulating substrate 2 and fusion-cutting the fuse element 3 by heat generation, and a power supply terminal connected to one end of the heating element 4 to the heating element 4 is connected to the heating element feeding electrode 5, the insulating layer 6 covering the heating element 4, and the other end of the heating element 4, is formed along the heating element 4 on the insulating layer 6, It has a heat generating body lead-out electrode 7 by which the molten conductor 3a of the fuse element 3 is hold|maintained.

In addition, the protection element 30 is provided in parallel with a plurality of heat generating elements 4 spaced apart from each other on the insulating substrate 2 . Each heating element 4 has one end connected to the heating element feeding electrode 5 and the other end connected to the heating element electrode 8 . The heating element electrode 8 is connected to the heating element extraction electrode 7 . In each heating element 4, when electricity is supplied through the heating element feeding electrode 5, the heating element feeding electrode 5 side becomes a high potential part, and the heating element electrode 8 and the heating element withdrawing electrode 7 side becomes a low potential part. In addition, each heating element 4 is covered with the insulating layer 6 and overlaps with the heating element lead-out electrode 7 formed on the insulating layer 6 .

The heating element extraction electrode 7 formed in the protection element 30 can be formed by well-known methods, such as printing, using well-known electrode materials, such as Ag, Cu, or an alloy material which has Ag or Cu as a main component.

The heating element extraction electrode 7 has a tip portion 7a extending toward the high potential portion side of each heating element 4 when energized, and a base portion 7b extending toward the low potential portion side, the tip portion 7a and the heating element 4 . ) overlap area S1 is smaller than overlap area S2 between the base portion 7b and the heating element 4 . Accordingly, the protection element 30, like the protection element 1, is unlikely to generate a spark (discharge) even when a high voltage is applied from an external circuit, so that it is possible to safely and quickly cut off the current path.

In addition, in the protection element 30 shown in FIG. 10, the heat generating body lead-out electrode 7 overlaps each heat generating body 4 at the base part 7b, and the front-end|tip part 7a is between the two heat generating elements 4 formed on the region, so that the tip portion 7a does not overlap the two heating elements 4 . The tip portion 7a of the heating element lead-out electrode 7 extends toward the high potential portion of the heating element 4, but does not overlap with the overlapping area with the heating element 4, that is, the overlapping area with the heating element 4 is zero, It is smaller than the overlapping area of the base part 7b with the heat generating element 4 . As a result, the distance and the opposing area (overlapping area) of the distal end portion 7a of the heat generating element 4 with the high-potential portion of the heat generating element 4 is reduced, making it difficult to form a discharge path and thus less likely to generate sparks.

In addition, as shown in FIG. 11, in the protection element 30, the front-end|tip part 7a of the heat generating body lead-out electrode 7 is formed in the area|region between the two heat generating elements 4, and the front-end|tip part 7a is a part. may overlap with at least one, preferably two heating elements 4 . Also in the configuration shown in FIG. 11 , in the protection element 30 , the overlapping area S1 between the tip portion 7a and the heating element 4 is smaller than the overlapping area S2 between the base portion 7b and the heating element 4 . Therefore, even when a high voltage is applied, it is difficult to generate a spark (discharge), so that the current path can be cut off safely and quickly. Further, since the tip portion 7a partially overlaps the heating element 4 , the heat of the heating element 4 is efficiently transmitted to the tip portion 7a , and the fuse element 3 can be heated more quickly.

12 is a circuit diagram of the protection element 30 . The protection element 30 is connected to a power source for heating the heating element 4 through a heating element feeding electrode 5 at which each end of the plurality of heating elements 4 is formed on the insulating substrate 2, and each heating element 4 The other end of the is connected to the fuse element 3 through the heating element extraction electrode 7 .

[Modified example of the heating element extraction electrode 7]

13 and 14 are modified examples of the heating element lead-out electrode 7 . As shown in Fig. 13, the heat generating element lead-out electrode 7 may have the tip portion 7a formed in a rectangular shape, and the tip portion 7a and the base portion 7b may be continuous through an inclined surface. Moreover, as for the heat generating body lead-out electrode 7, as shown in FIG. 14, the front-end|tip part 7a may be formed in the substantially trapezoidal shape, or may be formed in the triangular shape.

In addition, as shown in FIG. 15 , the protection element 30 is a holding electrode 32 holding the molten conductor 3a of the fuse element 3 on the back surface 2b of the insulating substrate 2 . The molten conductor 3a of the fuse element 3 molten by forming the heat generating element lead-out electrode 7 and the holding electrode 32 continuously through the through hole 33 penetrating the insulating substrate 2 may be attracted to the holding electrode 32 side through the through hole 33 .

When the fuse element 3 is melted, the through hole 33 attracts the molten conductor 3a by capillary action to reduce the volume of the molten conductor 3a held on the heating element lead-out electrode 7 . can As a result, as shown in FIG. 16 , even when the amount of fusion increases due to the increase in size of the fuse element 3 along with increase in the fixed rating and high capacity of the protection element, a large amount of the molten conductor 3a is held by the holding electrode 32 . , can be held by the heating element lead-out electrode 7 and the first and second electrodes 11 and 12, and the fuse element 3 can be cut by fusing reliably.

The holding electrode 32 can be formed by a known method such as printing using a known electrode material such as Ag, Cu, or an alloy material containing Ag or Cu as a main component, similarly to the heating element lead-out electrode 7 . have.

A conductive layer 34 is formed on the inner surface of the through hole 33 . By forming the conductive layer 34, the through hole 33 can easily attract the molten conductor 3a. The conductive layer 34 is formed of, for example, any one of copper, silver, gold, iron, nickel, palladium, lead, and tin, or an alloy containing any of them as a main component, and electrolyzes the inner surface of the through hole 33 . It can form by well-known methods, such as plating and printing of an electrically conductive paste. Further, the conductive layer 34 may be formed by inserting a plurality of metal wires or an aggregate of conductive ribbons into the through holes 33 .

The conductive layer 34 of the through hole 33 is continuous with the heating element lead-out electrode 7 formed on the surface 2a of the insulating substrate 2 . Since the heating element extraction electrode 7 supports the fuse element 3 and the molten conductor 3a aggregates at the time of fusion cutting, when the heating element extraction electrode 7 and the conductive layer 34 are continuous, the molten conductor ( 3a) can be easily guided into the through hole 33 .

In addition, the conductive layer 34 of the through hole 33 is continuous with the holding electrode 32 formed on the back surface 2b of the insulating substrate 2 . Thereby, when the fuse element 3 is melted, the molten conductor 3a sucked through the through hole 33 can be aggregated on the holding electrode 32 (refer to Fig. 16), so that more molten conductors 3a ), the volume of the molten conductor 3a at the fusing site of the fuse element 3 held by the heating element extraction electrode 7 and the first and second electrodes 11 and 12 can be reduced. .

Moreover, the protection element 30 increases the path|route which attracts the molten conductor 3a of the fuse element 3 by forming the plurality of through-holes 33, and attracts more molten conductor 3a, so that a fusing site|part You may make it reduce the volume of the molten conductor 3a in

[Modified example of heating element]

In addition, in the protection element 30, in addition to forming the shape of the plurality of heat generating elements 4 in a substantially rectangular shape, as shown in FIG. 17, the protrusion 4a formed in an L shape over the end on the low-potential part side. , and may be formed so that the protruding portions 4a are opposed to each other. The protrusion 4a may be formed substantially orthogonal to the longitudinal direction of the heat generating element 4 as shown in FIGS. 17A and 17B , and is shown in FIGS. 17C and 17D . You may have a tapered surface as mentioned above. In addition, the heat generating body lead-out electrode 7 or the holding electrode 32 may be superimposed on the said protrusion part 4a.

[Third Embodiment: Structure of Back Heating Element]

Next, 3rd Embodiment of the protection element to which this technology was applied is demonstrated. In addition, in the following description, about the structure similar to the protection elements 1 and 30 mentioned above, the same code|symbol is attached|subjected and the detail may be abbreviate|omitted. The protection element 40 which concerns on 3rd Embodiment is the insulated substrate 2 and the fuse provided in the surface 2a side of the insulated substrate 2, as shown to Fig.18 (A), (B). The element 3, a plurality of heating elements 4 formed on the insulating substrate 2 and fusion-cutting the fuse element 3 by heat generation, and a power supply terminal connected to one end of the heating element 4 to the heating element 4 is connected to the heating element feeding electrode 5, the insulating layer 6 covering the heating element 4, the other end of the heating element 4, It has a heating-element lead-out electrode 7 by which the molten conductor 3a of the fuse element 3 is hold|maintained.

And the protection element 40 has each heating element 4, the heating element feeding electrode 5, and the heating element extraction electrode 7 on the opposite side to the surface 2a of the insulated substrate 2 in which the fuse element 3 was provided. A support electrode 41 is formed on the back surface 2b and supports the fuse element 3 on the front surface 2a of the insulating substrate 2 . The heating element lead-out electrode 7 and the support electrode 41 formed on the back surface 2b are continuous through a through hole 42 penetrating the insulating substrate 2, whereby the insulating substrate 2 is melted A fusing member 43 for fusing the fuse element 3 is constituted by sucking the molten conductor 3a of the fuse element 3 to the heat generating body extraction electrode 7 side through the through hole 42 .

Each heating element 4 has one end connected to the heating element feeding electrode 5 and the other end connected to the heating element electrode 8 . The heating element electrode 8 is connected to the heating element extraction electrode 7 . In each heating element 4, when electricity is supplied through the heating element feeding electrode 5, the heating element feeding electrode 5 side becomes a high potential part, and the heating element electrode 8 and the heating element withdrawing electrode 7 side becomes a low potential part. In addition, each heating element 4 is covered with the insulating layer 6 and overlaps with the heating element lead-out electrode 7 formed on the insulating layer 6 .

The heating element extraction electrode 7 has a tip portion 7a extending toward the high potential portion side of each heating element 4 when energized, and a base portion 7b extending toward the low potential portion side, the tip portion 7a and the heating element 4 . ) overlap area S1 is smaller than overlap area S2 between the base portion 7b and the heating element 4 . Accordingly, the protection element 20, like the protection element 1, is unlikely to generate a spark (discharge) even when a high voltage is applied from an external circuit, so that it is possible to safely and quickly cut off the current path. In addition, also in the protection element 40, similarly to the protection element 30, the heat generating body extraction electrode 7 can employ|adopt various structures shown in FIGS.

The support electrode 41 is connected to the fuse element 3 through a bonding material such as a connection solder 9 , and when the fuse element 3 is melted, the molten conductor 3a is aggregated and held. Further, in the support electrode 41, a through hole 42 for attracting the molten conductor 3a of the fuse element 3 by capillary action is formed, thereby holding the molten conductor 3a on the support electrode 41. The volume of 3a) is reduced. And, as shown in FIG. 19, the protection element 40 increases the cross-sectional area of the fuse element 3 in order to respond to a large current application, so that even when the amount of the molten conductor 3a increases, the through hole ( 42) and held by the heating element lead-out electrode 7, the amount of the molten conductor 3a held by the support electrode 41 can be reduced, and the fuse element 3 can be fused reliably. can

The support electrode 41 can be formed by a known method such as printing using a known electrode material such as Ag, Cu, or an alloy material containing Ag or Cu as a main component, similarly to the heating element lead-out electrode 7 . .

Further, in the through hole 42 , similarly to the through hole 33 described above, a conductive layer 44 continuous with the supporting electrode 41 and the heating element extraction electrode 7 is formed on the inner surface thereof. Since the conductive layer 44 has the same structure and action as the conductive layer 34, the details are omitted. Moreover, the protection element 40 increases the path|route which attracts the molten conductor 3a of the fuse element 3 by forming the plurality of through-holes 42, and attracts more molten conductor 3a, so that a fusing site|part You may make it reduce the volume of the molten conductor 3a in

Moreover, the auxiliary electrode 45 which holds the molten conductor 3a while being connected to the fuse element 3 together with the support electrode 41 is provided on the surface 2a of the insulated substrate 2 . Further, the fuse element 3 is provided separately from the insulating substrate 2 and is connected to the first and second electrode terminals 46 and 47 connected to an external circuit through a bonding material such as a connection solder 9 . have. Moreover, the heating element feeding electrode 5 is similarly provided separately from the insulating substrate 2, and is connected with the 3rd electrode terminal 48 connected with the external circuit.

In the insulating substrate 2 having such a configuration, the auxiliary electrode 45 and the supporting electrode 41 are connected to the fuse element 3 through a bonding material, and when the heating element 4 is energized and generates heat, the heat is generated by the fuse. The element 3 is melted, and the fusing member 43 for blocking the molten conductor 3a by sucking the molten conductor 3a through the through hole 42 to the side of the heat generating body lead-out electrode 7 is constituted.

In addition, the protection element 40 may hold the fuse element 3 by the some fusing member 43, as shown in FIG. In the protection element 40 shown in FIG. 20 , the fusing member 43 is arranged on one surface and the other surface of the fuse element 3 , respectively. 21 is a circuit diagram of the protection element 40 . Each of the fusing members 43 disposed on the front and back surfaces of the fuse element 3 has one end of the heating element 4 formed on each insulated substrate 2 by a heating element extraction electrode 7 and a supporting electrode 41 , respectively. It is connected to the fuse element 3 via the fuse element 3, and the other end of the heating element 4 is connected to a power source for generating heat from the heating element 4 through the heating element feeding electrode 5 formed on each insulating substrate 2 .

Moreover, as shown in FIG. 22, when the protection element 40 cuts the fuse element 3 by heat_generation|fever of the heat generating body 4, each fusing member 43 connected to both surfaces of the fuse element 3 is carried out. , 43 , heats up and heats from both surfaces of the fuse element 3 . Therefore, even when the cross-sectional area of the fuse element 3 is increased in order to respond to a large current application, the protection element 40 can heat the fuse element 3 quickly and cut it by melting.

Moreover, the protection element 40 attracts the molten conductor 3a from both surfaces of the fuse element 3 into each through hole 42 formed in the insulating substrate 2 of each fusion|fusion cutting member 43. As shown in FIG. Therefore, the protection element 40 increases the cross-sectional area of the fuse element 3 in order to respond to a large current application, and even when the molten conductor 3a generate|occur|produces in a large amount, it is attracted|sucked by the some fusing member 43, and reliably It is possible to blow the fuse element 3 by fusion. Moreover, the protection element 40 can blow-cut the fuse element 3 more rapidly by attracting|sucking the molten conductor 3a with the some fusing member 43.

The protection element 40 can blow the fuse element 3 quickly by fusing even when a covering structure in which a low-melting-point metal constituting an inner layer is covered with a high-melting-point metal is used as the fuse element 3 . That is, the fuse element 3 coated with the high-melting-point metal takes time to heat to a temperature at which the outer layer of the high-melting-point metal is melted, even when the heating element 4 generates heat. Here, the protection element 40 is provided with the some fusion|melting member 43, and can heat the refractory-point metal of an outer layer to a melting|fusing temperature quickly by heating each heat generating element 4 at the same time. Therefore, according to the protection element 40, the thickness of the high-melting-point metal layer which comprises an outer layer can be thickened, and rapid melting|fusing characteristic can be maintained, aiming at the further fixed rating.

Moreover, as for the protection element 40, as shown in FIG. 20, it is preferable that a pair of fusing member 43, 43 opposes and it is connected to the fuse element 3. As shown in FIG. Thereby, in the pair of fuse members 43 and 43, the protection element 40 can heat the same location of the fuse element 3 simultaneously from both sides, and can attract the molten conductor 3a, The fuse element 3 can be heated and melted faster.

Further, in the protection element 40 , the auxiliary electrode 45 and the supporting electrode 41 formed on each insulating substrate 2 of the pair of fusing members 43 and 43 are opposed to each other via the fuse element 3 . It is preferable to do As a result, since the pair of fusing members 43 and 43 are symmetrically connected, the manner in which a load is applied to the fuse element 3 during reflow mounting or the like is not unbalanced, thereby improving resistance to deformation. can

In addition, in any case where the heating element 4 is formed on the front surface 2a and the back surface 2b of the insulating substrate 2, the support electrode 41 and It is preferable when heating the heat generating body lead-out electrode 7, and coagulating and attracting|sucking more molten conductor 3a.

second embodiment

Next, an embodiment of the protection element 30 will be described. In the second embodiment, the protection element 30 shown in Fig. 10 and the protection element provided with the rectangular heating element extraction electrode shown in Figs. 26 and 23 are prepared, and voltages of 50 V, 100 V, and 200 V are applied, respectively. The presence or absence of sparks at the time of doing this was determined. Further, the fusing time of the fuse element was evaluated, and the case where the fuse was cut within a predetermined time (60 seconds) was evaluated as ○ (good), and the case where the fuse was not cut within the predetermined time was evaluated as × (bad).

The dimension of each part of the protection element which concerns on an Example and a comparative example is defined as follows. In addition, the numerical value of each part shown in Table 3 is a numerical value which shows the ratio when E of Example 2 is set to 1.

D: distance between the tip of the heating element lead-out electrode and the heating element feeding electrode

E: Length in the energization direction of the heating element

F: Minimum width of the heating element lead-out electrode

G: Maximum width of the heating element lead-out electrode

L: Width between the side edge of the tip of the heating element lead-out electrode and the side edge of the base

M: the width between the outer side edge of the substrate of the heating element and the (tip portion) side edge of the heating element lead-out electrode

N: The distance in the width direction of the side edge of the heating element lead-out electrode and the side edge of the heating element in the width direction.

P: length of the heating element extraction electrode

Q: The overlapping length of the heating element lead-out electrode and the heating element

[Example 2]

As the protection element according to Example 2, the one shown in FIG. 10 was used. In the protection element according to the second embodiment, a base portion (width G: 0.71) and a tip portion (width F: 0.21) are provided on the heat generating element lead-out electrode, and the base portion is formed to be wider than the tip portion by 0.25 on one side. In addition, the heating element lead-out electrode does not protrude toward the heating element feeding electrode side than the fuse element, and the distance (D) between the tip of the heating element extraction electrode and the heating element feeding electrode is 0.04, and the overlapping length (Q) of the heating element extraction electrode and the heating element is 0.54 is made of

[Comparative Example 3]

As the protection element according to Comparative Example 3, the one shown in FIG. 26 was used. In the protection element according to Comparative Example 3, a rectangular heating element extraction electrode (width: 0.44) was formed. Further, the heating element lead-out electrode does not protrude toward the heating element feeding electrode side than the fuse element, and the distance (D) between the tip of the heating element extraction electrode and the heating element feeding electrode is 0.04, and the overlapping length Q between the heating element extraction electrode and the heating element is 0.96. is made of

[Comparative Example 4]

As the protection element according to Comparative Example 4, the one shown in FIG. 23 was used. Similarly to Comparative Example 3, the protection element according to Comparative Example 4 used a rectangular heating element extraction electrode (width: 0.21). The difference from Comparative Example 3 is that, in the protection element according to Comparative Example 4, the heating element extraction electrode does not overlap the heating element (Q=0.00). Further, in Comparative Example 4, the distance D between the tip of the heating element lead-out electrode and the heating element feeding electrode was 0.04.

As shown in Table 4, in Example 2, even when any voltage was applied, there was no spark generation, and the fuse element could be blown by fusing within a predetermined time. On the other hand, in Comparative Example 3, sparks were generated when voltages of 100V and 200V were applied, and the fuse element could not be blown by fusing within a predetermined time. Further, in Comparative Example 4, no spark was generated even when any voltage was applied, but since a rectangular heating element extraction electrode having a narrow width of 0.21 was used, the capacity for holding the molten conductor of the fuse element was increased. It was insufficient, and as shown in FIG. 24, the molten conductor was continuous between a 1st, 2nd electrode, and the fuse element could not be blown-off within a predetermined time.

1: Protection element 2: Insulation substrate
2a: surface 2b: back side
3: fuse element 3a: molten conductor
4: heating element 4a: protrusion
5: heating element feeding electrode 5a: third external connection electrode
6: Insulation layer 7: Heating element extraction electrode
7a: tip 7b: base
8: Heating element electrode 9: Connection solder
11: first electrode 11a: first external connection electrode
12: second electrode 12a: second external connection electrode
13: low melting point metal layer 14: high melting point metal layer
17: regulatory wall 20: battery pack
20a: positive terminal 20b: negative terminal
21a to 21d: battery cell 22: charging device
23: current control element 24: control unit
25: battery stack 26: charge and discharge control circuit
27: detection circuit 28: current control element
30: protection element 32: holding electrode
33: through hole 34: conductive layer
40: protection element 41: support electrode
42: through hole 43: fusing member
44: conductive layer 45: auxiliary electrode
46: first electrode terminal 47: second electrode terminal
48: third electrode terminal

Claims (15)

an insulated substrate;
a fuse element provided on one side of the insulating substrate;
a heating element formed on the insulating substrate to melt the fuse element by heat generation;
a heating element feeding electrode connected to one end of the heating element and serving as a power supply terminal to the heating element;
an insulating layer covering the heating element;
a heating element lead-out electrode connected to the other end of the heating element and formed along the heating element on the insulating layer to hold the molten conductor of the fuse element;
When the heating element is energized through the heating element feeding electrode, the heating element feeding electrode side becomes a high potential part, and the heating element lead-out electrode side becomes a low potential part,
In the heating element lead-out electrode, an overlapping area of the front end portion extending toward the high potential portion of the heating element and the heating element is smaller than the overlapping area of the base portion extending toward the low potential portion of the heating element and the heating element, A protection element, characterized in that. The width direction according to claim 1, wherein a direction orthogonal to an energization direction of the heat generating element is defined as a width direction,
The heating element lead-out electrode is a protection element, wherein the width of the tip portion is narrower than the width of the base portion. 3 . The assumed region according to claim 2 , wherein an overlapping area with the heating element is a non-overlapping area with the heating element in the assumed region when it is assumed that the tip portion has a width equal to that of the base portion. A narrower, protective element. The protection element according to any one of claims 1 to 3, wherein an area of the tip portion of the heat generating element lead-out electrode is smaller than an area of the base portion. The protection element according to any one of claims 1 to 3, wherein, in the heating element lead-out electrode, the entirety of the tip portion overlaps the heating element. The protection element according to claim 4, wherein, in the heating element lead-out electrode, all of the tip portion overlaps the heating element. The method of any one of claims 1 to 3, wherein the fuse element is mounted on the heating element lead-out electrode;
A protection element, wherein a tip portion of the heating-element lead-out electrode does not protrude toward the heating-element feeding electrode side than a side edge portion of the fuse element. The protection element according to claim 1, wherein a plurality of the heating elements are provided in parallel and spaced apart from each other on the insulating substrate. The method according to claim 8, wherein, in the heating element lead-out electrode, the tip portion is formed on a region between the two heating elements,
The said tip part does not overlap with the said two heat generating elements, The protection element. The protection element according to claim 8, wherein, in the heating element lead-out electrode, the tip portion is formed on a region between the two heating elements, and a part of the tip portion overlaps with at least one heating element. The holding electrode for holding the molten conductor of the fuse element is formed on the other side opposite to one side of the insulating substrate according to any one of claims 8 to 10,
the heating element extraction electrode and the holding electrode are continuous through a through hole penetrating the insulating substrate;
The said insulating board|substrate attracts the molten conductor of the said fuse element which melted through the said through-hole to the said holding electrode side, The protection element. The insulating substrate according to any one of claims 8 to 10, wherein the heating element, the heating element feeding electrode, and the heating element withdrawing electrode are formed on the other surface opposite to one surface of the insulating substrate on which the fuse element is provided. become,
A support electrode for supporting the fuse element is formed on one surface of the insulating substrate;
The heating element lead-out electrode and the support electrode are continuous through a through hole penetrating the insulating substrate,
The said insulating substrate constitutes a fusing member which attracts|sucks the molten conductor of the said fuse element to the said heat generating-element extraction electrode side through the said through-hole, The protection element which comprises. The protection element of Claim 12 by which the said fuse element is clamped by the said fusing member. The protection element according to any one of claims 1 to 3, wherein the voltage applied to the heating element feeding electrode is 100 V or more. one or more battery cells;
a protection element connected to the charging/discharging path of the battery cell to block the charging/discharging path;
and a current control element that detects the voltage value of the battery cell and controls energization of the protection element;
The protection element is
an insulated substrate;
a fuse element provided on one side of the insulating substrate;
a heating element formed on the insulating substrate to melt the fuse element by heat generation;
a heating element feeding electrode connected to one end of the heating element and serving as a power supply terminal to the heating element;
an insulating layer covering the heating element;
a heating element lead-out electrode connected to the other end of the heating element and formed along the heating element on the insulating layer to hold the molten conductor of the fuse element;
When the heating element is energized through the heating element feeding electrode, the heating element feeding electrode side becomes a high potential part, and the heating element lead-out electrode side becomes a low potential part,
In the heating element lead-out electrode, an overlapping area of the front end portion extending toward the high potential portion of the heating element and the heating element is smaller than the overlapping area of the base portion extending toward the low potential portion of the heating element and the heating element, characterized in that the battery pack.

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